Red - ECMWF Green - Sintex Navy - POAMA-2.0

The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

Red - ECMWF

Green - Sintex

Navy - POAMA-2.0

Anomaly Correlation

Standard Dev

Drift

NINO-3


Red - ECMWF

Green - Sintex

Navy - POAMA-2.0

Anomaly Correlation Standard Dev

Drift

NINO-4


Red - ECMWF

Green - Sintex

Navy - POAMA-2.0

Anomaly Correlation Standard Dev

IOD


OBS relationship between AU rainfall and the first two dominant EOF modes of SST

DJF MAM JJA SON

CC with PC1

CC with PC2


Can POAMA predict “flavour” of El Nino?

1 month lead

5 month lead

9 month lead

EOF PC1 0.98 0.77 0.67

EOF PC2 0.93 0.65 0.54

SST EOF1 SST EOF2

Wang and Hendon (2007) showed that EOF2 important for Australian Rainfall


1997

OBS

2002

POAMA at

3 months lead

1997

2002

1997 vs 2002 SST forecasts


1997 SON POAMA lt 0

2002 SON POAMA lt 0

1997 SON Obs

2002 SON Obs

BUT•Skill disappears after first season


POAMA’s first two SST EOF modes (SON)

0.93 (pattern corr.) LT 0 0.80

0.88 LT 3 0.59

61% (explained var.) 12%

0.88 LT 6 0.61

OBS

POAMA54%

66%

12%

10%

71% 8%


Corr between rainfall and PC1 in POAMA hindcasts at lead time 0 to 6 months (anticlockwise)

JJALT0

LT1

LT2 LT3 LT4

LT5

LT6


Corr between rainfall and PC1 in POAMA hindcasts at lead time 0 to 6 months (anticlockwise)

SON


EA rainfall

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

DJF MAM JJA SON

Co

rr. C

oe

ff. LT0

LT1

LT3

LT6

EA Tmax

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

DJF MAM JJA SONC

orr

. Co

eff

. LT0

LT1

LT3

LT6

EA Tmin

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

DJF MAM JJA SON

Co

rr. C

oe

ff. LT0

LT1

LT3

LT6


SON Rainfall 1982-2006 from POAMA-1.5

POAMA vs ClimatologyNCC operational vs Climo POAMA vs NCC

Brier Skill Score percentage improvement

Forecast for first season

BUT•Skill disappears after first season

•Too emphatic ?


Skill improvement of POAMA prediction from the current operational prediction for exceeding median rainfall (at lead time 0)

DJF MAM

(summer) (autumn)

JJA SON

(winter) (spring)


Skill improvement of Multi-Model Ensemble prediction compared to POAMA only for rainfall (at lead time 0)

DJF MAM

(summer) (autumn)

JJA SON

(winter) (spring)


Nino-4 Anomaly CorrelationNino-4 Anomaly Correlation

Red - Old systemRed - Old system

Navy - PEODASNavy - PEODAS

Blue - ECMWFBlue - ECMWF


Pink - No AssimPink - No Assim


West Pacific (Nino-4)West Pacific (Nino-4)

Why no significant improvement relative to No Assim (and behind ECWMF) in first few months?

Standard deviation of NINO4 anomalies with lead time

INITIALISATION SHOCK ?

Imbalanced initialisation or Model error ?

Probably model error


IOD Anomaly CorrelationIOD Anomaly Correlation

Red - Old systemRed - Old system


Blue - ECMWFBlue - ECMWF


Pink - No AssimPink - No Assim


IOD: Why no significant improvement and IOD: Why no significant improvement and behind ECWMF ?behind ECWMF ?

Due to Altimeter data ?Due to Altimeter data ?Correlation of surface U with OSCARCorrelation of surface U with OSCAR

(www.oscar.noaa.gov)(www.oscar.noaa.gov)

PEODAS ECMWFPEODAS ECMWF


IOD: Why no significant improvement and IOD: Why no significant improvement and behind ECWMF ?behind ECWMF ?

Or Due to Model error ?Or Due to Model error ?

STD of IOD Bias in IOD EastSTD of IOD Bias in IOD East


Characteristics of simulated IOD in POAMA


• The observed DMI peaks strongly in SON and is a minimum in Jan-Apr. The simulated

DMI in the forecast model exhibits a realistic seasonal variation but its maximum in SON is

too weak and it does not drop off as quickly in Dec-Jan as observed.

• Inspection of the annual variation of the amplitude of the Niño3.4 index indicates realistic

amplitude and seasonal variation (peak in Nov-Jan), suggesting that any errors in remote

forcing from ENSO do not stem from an erroneous depiction of the phase locking to the

seasonal cycle of El Niño development.

Obs

Lt1

Lt3

Lt6

Lt9

Seasonal cycle


Red - ECMWF

Green - Sintex

Navy - POAMA-2.0

Standard Deviation

Drift

IOD-EAST


Examples of poor central Pacific Forecasts

Red - ECMWF

Green - Sintex

Navy - POAMA-2.0

Light Blue - POAMA-1.5


SST 20C Depth Zonal Wind

Cold Bias - initialisation shock ?


Missed ENSO’s

Why?

Model problem

Predictability

Initialisation


1997 El Nino

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Red - ECMWF Green - Sintex Navy - POAMA-2.0

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